Change in coreboot[master]: cpu/x86/mtrrlib: Use `need restore mtrr()` from set var mtrr function

[Subrata Banik (Code Review)]

Subrata Banik has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/63492 )

Change subject: cpu/x86/mtrrlib: Use `need_restore_mtrr()` from  set_var_mtrr  function
......................................................................

cpu/x86/mtrrlib: Use `need_restore_mtrr()` from  set_var_mtrr  function

`fast_spi_cache_bios_region()` is calling `set_var_mtrr()` to set
temporary MTRRs with commit def18c406 (soc/intel/common/block/fast_spi:
Refactor ROM caching implementation).

Hence, this patch ensures the `put_back_original_solution` variable is
also getting set by `need_restore_mtrr()` while calling from the
`set_var_mtrr()`. Later `remove_temp_solution()` discard any temporary
MTRRs prior to boot to payload.

Ensure `set_var_mtrr()` being called during ramstage only sets the
`put_back_original_solution` variable.

BUG=b:225766934
TEST=Able to build and boot google/brya to verify that
`remove_temp_solution()` is able to discard ROM caching temporary MTRRs
before booting to payload.

Signed-off-by: Subrata Banik 
Change-Id: I67fd36080b318ace53f3e34da53d747f9a3aa400
---
M src/cpu/x86/mtrr/mtrrlib.c
1 file changed, 4 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/92/63492/1

diff --git a/src/cpu/x86/mtrr/mtrrlib.c b/src/cpu/x86/mtrr/mtrrlib.c
index 71921de..ca8a20d 100644
--- a/src/cpu/x86/mtrr/mtrrlib.c
+++ b/src/cpu/x86/mtrr/mtrrlib.c
@@ -48,6 +48,10 @@
    maskm.lo = ~(size - 1) | MTRR_PHYS_MASK_VALID;
    maskm.hi = (1 << (cpu_phys_address_size() - 32)) - 1;
    wrmsr(MTRR_PHYS_MASK(reg), maskm);
+
+	/* Need to restore mtrr later using remove_temp_solution. */
+	if (ENV_RAMSTAGE)
+		need_restore_mtrr();
 }

void clear_all_var_mtrr(void)